[JXR-159] Require Maven 3.1.1+ runtime

diff --git a/maven-jxr-plugin/pom.xml b/maven-jxr-plugin/pom.xml
index a5f757b..3ef633f 100644
--- a/maven-jxr-plugin/pom.xml
+++ b/maven-jxr-plugin/pom.xml
@@ -36,7 +36,7 @@
   <inceptionYear>2005</inceptionYear>
 
   <properties>
-    <mavenVersion>3.1.0</mavenVersion> <!-- support javax.inject -->
+    <mavenVersion>3.1.1</mavenVersion> <!-- support javax.inject -->
     <doxia-sitetoolsVersion>1.9.2</doxia-sitetoolsVersion>
   </properties>
 
@@ -121,10 +121,27 @@
     </dependency>
 
     <!-- shared -->
+    <!-- overwrite from maven-reporting-impl -->
+    <dependency>
+      <groupId>org.apache.maven.shared</groupId>
+      <artifactId>maven-shared-utils</artifactId>
+      <version>3.3.3</version>
+    </dependency>
+    <dependency>
+      <groupId>commons-io</groupId>
+      <artifactId>commons-io</artifactId>
+      <version>2.6</version>
+    </dependency>
     <dependency>
       <groupId>org.apache.maven.doxia</groupId>
       <artifactId>doxia-site-renderer</artifactId>
       <version>${doxia-sitetoolsVersion}</version>
+      <exclusions>
+        <exclusion>
+          <artifactId>plexus-container-default</artifactId>
+          <groupId>org.codehaus.plexus</groupId>
+        </exclusion>
+      </exclusions>
     </dependency>
     <dependency>
       <groupId>org.apache.maven.reporting</groupId>
@@ -134,7 +151,7 @@
     <dependency>
       <groupId>org.apache.maven.wagon</groupId>
       <artifactId>wagon-provider-api</artifactId>
-      <version>1.0</version>
+      <version>2.4</version><!-- like Maven 3.1.1 -->
     </dependency>
     <dependency>
       <groupId>org.codehaus.plexus</groupId>
@@ -154,7 +171,18 @@
     <dependency>
       <groupId>org.apache.maven.plugin-testing</groupId>
       <artifactId>maven-plugin-testing-harness</artifactId>
-      <version>3.0.0</version>
+      <version>3.1.0</version>
+      <scope>test</scope>
+      <exclusions>
+        <exclusion>
+          <artifactId>plexus-container-default</artifactId>
+          <groupId>org.codehaus.plexus</groupId>
+        </exclusion>
+      </exclusions>
+    </dependency>
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
       <scope>test</scope>
     </dependency>
   </dependencies>
diff --git a/pom.xml b/pom.xml
index ef40475..b52fb34 100644
--- a/pom.xml
+++ b/pom.xml
@@ -26,7 +26,7 @@
     <groupId>org.apache.maven</groupId>
     <artifactId>maven-parent</artifactId>
     <version>34</version>
-    <relativePath>../pom/maven/pom.xml</relativePath>
+    <relativePath/>
   </parent>
 
   <groupId>org.apache.maven.jxr</groupId>
@@ -67,6 +67,8 @@
     <sitePluginVersion>3.3</sitePluginVersion>
     <maven.site.path>jxr-archives/jxr-LATEST</maven.site.path>
     <surefire.version>2.22.2</surefire.version>
+    <mavenPluginToolsVersion>3.6.0</mavenPluginToolsVersion>
+    <checkstyle.violation.ignore>None</checkstyle.violation.ignore>
     <project.build.outputTimestamp>2020-05-23T14:54:38Z</project.build.outputTimestamp>
   </properties>
 
@@ -114,6 +116,11 @@
             <autoVersionSubmodules>true</autoVersionSubmodules>
           </configuration>
         </plugin>
+        <plugin>
+          <groupId>org.apache.maven.plugins</groupId>
+          <artifactId>maven-enforcer-plugin</artifactId>
+          <version>3.0.0-M3</version>
+        </plugin>
       </plugins>
     </pluginManagement>
     <plugins>